Method and apparatus for surgical electrocautery

ABSTRACT

The invention provides a surgical electrocautery method and apparatus that achieves sealing along the entire tissue length, and that also is able to deliver adequate force to produce an effective electrocautery seal. This problem is solved by using an incompressible fluid contained in a sac or sacs positioned to support the one or more electrodes used for electrocauterization. The profile of the electrodes thus conforms to the tissue surface and thickness variations, while exerting an optimized pressure along the entire length of the surface.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to medical devices. More particularly, theinvention relates to a method and apparatus for surgical electrocautery.

2. Description of the Prior Art

Electrocauterization is the process of cauterizing, coagulation, and/ordestroying tissue with electricity. A small probe with an electriccurrent running through it is used to cauterize (burn or destroy) thetissue. The procedure is frequently used to divide tissue structures ina fashion which is hemostatic (seals blood vessels, thereby preventingbleeding). See, for example, Y. C. Jou, M. C. Cheng, J. H. Sheen, C. T.Lin, P. C. Chen, Electrocauterization of bleeding points forpercutaneous nephrolithotomy, Urology 64(3):443-6 (September 2004). Theuse of electrocautery has been extremely beneficial for the performanceof surgical procedures, such as hysterectomy (the surgical removal ofthe uterus), where relatively long spans of tissue must be sealed anddivided to remove the organ. Experiments to date with a set or sets ofsingle continuous electrode pairs running the length of a device's longjaws have resulted in inconsistent arterial sealing and tissuecauterization. These inconsitent outcomes are likely due to inconsistentelectrode contact with the long (1-15 cm), complext tissue sheets. Thatis, while the electrodes and their backing surfaces are rigid, thetissue sheets are highly variable in their thickness and composition,given that the tissue sheets frequently contain arteries, veins, nerves,ligaments, lymphatics, etc.

To achieve sealing along the entire tissue length, the electrode or itsbacking surface must be conformable, but also must still be able todeliver adequate force to produce an adequate electrocautery seal. Whilea compressible material, such as a polymer or foam, can work, thesematerials do not transfer consistent force because the compressedregions of the material exert higher force than in those regions wheretissue is thinner, and the material is less compressed.

One solution in addition to the incorporation of conformable electrodesis to create multiple electrodes, where each electrode may have adifferent sealing profile, either from an electric power or energystandpoints, or from a conformability standpoint; and/or electrodes witha conformal surface, either under the electrode or as a standoff to thesides of the electrodes. While this approach is promising, there isstill more to do.

It would therefore be advantageous to provide a surgical electrocauterymethod and apparatus that achieves sealing along the entire tissuelength, and that also is able to deliver adequate force to produce aneffective electrocautery seal.

SUMMARY OF THE INVENTION

The invention provides a surgical electrocautery method and apparatusthat achieves sealing along the entire tissue length, and that also isable to deliver adequate force to produce an effective electrocauteryseal. One way to solve this problem is by using an incompressible fluidcontained in sac positioned to support the one or more electrodes usedfor electrocauterization. The profile of the electrodes thus conforms tothe tissue surface and thickness variations, while exerting an equalpressure along the entire length of the surface. Alternative embodimentsof the invention comprise the use of various gels, either containedwithin a sac or in place and not contained within a sac; and variousarrangements of springs and combinations of springs and fluid substratesupon which the electrodes are placed. The invention also contemplatesthe unique forming electrodes on the fluid filled sac itself, forexample by sputtering, spraying, or dipped coating; as well as the useof various springs as conformance members and as conductors, i.e.electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an electrocautery device according to a firstembodiment of the invention; and

FIG. 2 is a side view of second embodiment of an electrocautery deviceaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a surgical electrocautery method and apparatusthat achieves sealing along the entire tissue length, and that also isable to deliver adequate force to produce an effective electrocauteryseal. One way to solve this problem is by using an incompressible fluidcontained in sac positioned to support the one or more electrodes usedfor electrocauterization. The profile of the electrodes thus conforms tothe tissue surface and thickness variations, while exerting an optimizedpressure along the entire length of the surface. Alternative embodimentsof the invention comprise the use of various gels, either containedwithin a sac or in place and not contained within a sac; and variousarrangements of springs and combinations of springs and fluid substratesupon which the electrodes are placed. The invention also contemplatesthe unique forming electrodes on the fluid filled sac itself, forexample by sputtering, spraying, or dipped coating; as well as the useof various springs as conformance members and as conductors, i.e.electrodes.

FIG. 1 is a side view of an electrocautery device according to a firstembodiment of the invention.

The invention may comprise a fluid filled sac. The fluid may comprise,for example, a liquid, such as saline or Ringer's solution, or anotherbiocompatible liquid or gel. Biocompatibility is desired due to thepotential for rupture of the liquid or gel-containing portion of theinventive sac. One or more electrodes are mounted to the liquid filledsac. The sac, or balloon, can either be pre-filled with liquid or gel,or filled once it has been delivered to the site at which theelectrocautery (electrosealing) is to be performed. Thus, the amount ofliquid or gel contained in the sac may be adjusted as desired for theapplication to which the device is put. The sac itself may be made fromany biocompatible material, such as a surgical rubber or vinyl material,as is known in the art. The material should also be non-conductive andheat resistant. Further, the sac may be either a flexible, leak proofcovering for a well formed within the jaws of an electrocautery device,or it may be a balloon-like sac that entirely contains the liquid or geland that is attached to a jaw of the electrocautery device.

The device of FIG. 1 comprises a pair of jaws 10, 12, each of whichcomprises a rigid support member. The jaws are movable between a first,closed position for clamping a tissue therebetween for electrocauteryand a second, open position. The manner for effecting this movement isnot shown in the figures and is considered to be a matter of choice forthe person skilled in the art.

At least one of the jaws comprises a liquid or gel filled sac 13, 14. Inthis embodiment, a single electrode 15 may be provided on either side ofthe device jaws, or a plurality of electrodes 16 a-16 i may be providedon one or both jaws of the device. In the case of individual electrodes,the electrodes may be of varying lengths and thicknesses. Further, thematerials from which the electrodes are formed may be varied, all basedon the sealing needs of the tissue in the specific region to be sealed.

FIG. 1 shows a first jaw comprising a liquid or gel filled sac having aplurality of electrodes attached thereto, with a second jaw comprising asingle (or multiple) return electrode(s). Those skilled in the art willappreciate that a fluid filled sac may be provided on either or bothjaws, or on just portions of one or both jaws. The sacs may be filledwith a liquid, gel, small particles, compressed gas, or any combinationthereof, although an incompressible fluid is presently preferred and acompressed gas would not be appropriate for many applications to whichthe device is intended to be put. Nonetheless, a compressed gas iscontemplated as one medium for filling the sacs that is within the scopeof the invention.

Key to the invention is that the electrodes overlay a conformingsubstrate which forms a portion of the jaw with which the electrode isassociated. A liquid or gel filled sac allows liquid or gel to bedisplaced in regions beneath the electrodes that contact tissues thatare thicker, for example, and thus fill in those regions of the sac thatunderlay tissue contacted by the electrodes that is thinner. Thus,thicker tissues push electrodes into the sac and thus force the liquidor gel to push the electrodes at or near the thinner tissue closer tothe tissue at these locations. In this way, conformity of the electrodesto the tissue is achieved. This is advantageous not only during initialcontact of the electrodes with the tissue to offset variations in thethickness of the tissue, but also as the process of cauterizationproceeds and the thickness of the tissue is altered. That is, as thetissue is cauterized, some regions that are thicker may become thinner.Because the thickness profile of the tissue is altered in anunpredictable fashion by the cauterization process, the ability of theelectrodes to conform with the tissue becomes an important factor inassuring even and complete cauterization across the span of tissue thatis clamped between the jaws of the device for cauterization.

In other embodiments of the invention, the sac may be partitioned, basedupon a profile of the tissue or electrodes. For example, the sac mayhave one portion that contains more liquid or gel and that thus presentsthose electrodes to the tissue somewhat more displaced from the jaw thanelectrodes associated with a portion of the sac that is less highlyfilled. This differential in liquid or gel contained in the sacpartitions provides a profile to the electrodes that more nearly matchesthe thickness/thinness of the tissue, and yet allows for conformity ofthe electrodes within each region. That is, partitioning the sacs servesto both predispose the electrodes to a thinner or thicker tissue, whileretaining the ability of the electrodes to conform to local variationsin the tissue thickness.

Further, the partitions within the sac may be communicatively coupled toallow a restricted flow of liquid or gel therebetween. The restrictionallows some redistribution of the liquid or gel between the sacs, andyet provides for a differing electrode profile at different regionsalong the length of the jaws.

An alternative embodiment that approximates the desired results uses agel or foam material, or mechanical spring geometry either in one ormore sacs or, in the case of a gel having more mechanical integrity,i.e. solidity, or as one or more stand-alone mounting materials thatreplaces the sac entirely and upon which the electrodes are disposed.

The sac material itself can constitute the electrode, as well asfunctioning to contain the incompressible fluid. In this embodiment ofthe invention, a thin coating of a conductive material or a coatingfilled with conductive material can be preferentially applied onto aportion of the surface of the sac that comes into contact with thetissue to be sealed. The conductive material can be applied by any knowntechnique, such as sputtering, spraying, photolithography, or dippedcoating. Further, the material can be patterned when applied, such thata plurality of electrodes may be formed, and where the electrodes eachhave a different shape, size, or other constitution, as desired. Theleads necessary to connect the electrodes to a power source may beformed in this matter as well. This embodiment of the invention avoidsthe problems that may occur where the sac provides a conformal substratefor the electrodes, but the electrodes are formed of relatively rigidmaterial that defeats the conformal nature of the sac. Electrodes thatare formed integrally on the surface of the sac according to thisembodiment of the invention are always in conformance with the surfaceof the tissue to which they are contacted because they are part of thesac itself.

In other embodiments of the invention, the conformal material containedwithin a sac may be a solid polymer based material which provideincreased pressure on the thickest tissue, for example where thearteries are located. In these locations, it is necessary to provide themost sealing force and, therefore, the most energy must be transmittedthrough the device to the tissue. In the embodiment employing a polymerbased material, the material may have a surface pattern that is providedto optimize conformity while maintaining adequate support for the tissueto hold the tissue intact after the tissue is cauterized, for suchprocedures as cutting or sectioning the tissue, the surface pattern maybe formed by any of molding, cutting, patterning, and the like, and mayprovide any desired topological relief, such as a pattern of bumps,notches, projections, ridges, weaves, depressions, and the like.Further, such surface patterning is not limited to the poly basedmaterial, but may also be employed with sacs and other conformancemembers.

In this embodiment of the invention, a balanced set of materialproperties in the conformal material insures intimate contact withvarying tissue thicknesses from less than 1 millimeter to 1 centimeteror more to insure uniform sealing of the tissue, and also to exert thehighest pressure in the area where it is needed most, i.e. the thickestregion of the tissue. In one embodiment of the invention, the balancingof types of conformal materials provided to provide a profile ofpressure is accomplished by a hybrid of technologies, such as acombination of liquids, gels, solid polymers, and springs (see below).For example, the embodiment of the invention which contemplatescompartments within the sac may comprise a different material in eachsac, where those portions of the device that contact areas of thetissue, such as arteries, are provided with a portion of the sac that isfilled with a material that provides greater pressure to the tissue.Alternatively, such portions of the tissue may be confronted by aspring, or a spring may underlies a portion of the sac in those regionswhere additional pressure must be provided. Further, the substrate uponwhich the sac is placed could be profiled such that the fluid within thesac is predisposed to exert greater pressure at certain regions of thesac where such additional pressure is desired.

FIG. 2 is a side view of second embodiment of an electrocautery deviceaccording to the invention. This embodiment of the invention comprises apair of jaws 21, 22, as above, and approximates the desired resultsmechanically by using springs, which may be, for example, coil springs25 or leaf springs 26 (one example shown), or a combination thereof (asshown in FIG. 2), to effect compliance of the electrodes to the tissue.Those skilled in the art will appreciate that other types of springs maybe used as well. However, this embodiment of the invention has similarlimitations as that of an elastomer. The use of springs or elastomersmay prove valuable in optimizing the distribution of force because thespring force is higher in areas where the springs are more compressed,such as in thicker tissue regions which are harder to cauterize. Toallow control over this effect, springs with different tension may beprovided across the span of the jaws, such that stronger or shortersprings are provided, for example, a regions of the tissue that areknown to be thicker and that, thus, require more pressure and/or lesstravel to make proper contact with the tissue, while weaker springs orlonger springs are provided, for example, in regions of the tissue thatare known to be thinner and that, thus, require less pressure and/ormore travel to make proper contact with the tissue.

Another embodiment of the invention is a hybrid of the invention shownin FIGS. 1 and 2, in which a liquid or gel filled sac is providedbeneath a portion of the electrodes, while one or more springs may beprovided beneath other electrodes. This embodiment of the invention maybe applied to tissues that exhibit different properties along the regionto be electrocauterized.

In an alternative embodiment of the springs, the springs may take theshape of a coil or they may be a loop spring or other spring. Further,the springs themselves may act as electrodes, as well as providing aresilient pressure bearing surface at the point in which the devicecontacts the tissue. In this embodiment of the invention, it is notnecessary to provide separate electrodes. Further, the springs can bechosen for the amount of pressure they exert, such that a profile may beprovided to the device that provides more pressure to those regions thatwhich greater pressure is needed and less pressure at regions where lesspressure is necessary. Further, the coil or spring electrodes can beformed from a material such as nitinol and may be used in conjunctionwith liquids, gels, or solid polymers to optimize the force andconformability balance of the device.

In another embodiment of the invention, the gel, liquid, polymer, orsprings can compensatorily increase volume to maintain pressure as thetissue begins to electocauterize and thereby shrink. This embodiment ofthe invention maintains a somewhat constant pressure throughout thesealing cycle. The material used to effect the increase in volume of thesac or the material underlying the electrodes can be any known materialthat somewhat swells or stiffens during the electro-cauterizing cycle asthe material gets warmer, for example through conduction of heat fromthe tissue. Alternatively, a more complex system can be provided, as adynamic pressure monitoring system with a compensation mechanism builtinto the fluid system of the sack, for example a thermistor could beprovided that monitors the temperature of the tissue and that actuates apump to increase the pressure in the sac by adding fluid to the sac.Alternatively, an end-point detection system as is used forelectro-cautery could be coupled to the device to actuate a pump thatcompensates for shrinkage of the tissue by increasing the volume of thesac.

Although the invention is described herein with reference to thepreferred embodiment, one skilled in the art will readily appreciatethat other applications may be substituted for those set forth hereinwithout departing from the spirit and scope of the present invention.Accordingly, the invention should only be limited by the Claims includedbelow.

1. An apparatus for surgical electrocautery, comprising: a pair ofopposing jaws that are movable between an open position and a closed,clamping position; at least one electrode associated with one of saidjaws, said at least one electrode being disposed between said jaws forcontact with a tissue surface; at least one sac associated with one ofsaid jaws and positioned between said jaw and said at least oneelectrode to support said at least one electrode; an incompressiblefluid contained within said at least one sac, wherein said sac isprefilled with said incompressible fluid; wherein said at least oneelectrode exerts pressure upon said at least one sac when said jaws aremoved to a closed, clamping position and said at least one electrode isbrought into contact with said tissue surface, displacing saidincompressible fluid within said at least one sac, wherein said at leastone electrode conforms to said tissue surface while exerting anoptimized pressure along an entire length of said tissue surface.
 2. Theapparatus of claim 1, said incompressible fluid comprising: a liquidcomprising any of saline, Ringer's solution, a gel material, and anotherbiocompatible liquid.
 3. The apparatus of claim 1, wherein said at leastone electrode is mounted to said at least one sac.
 4. The apparatus ofclaim 1, wherein said at least one sac is made from a biocompatiblematerial.
 5. The apparatus of claim 1, at least one of said jawscomprising a plurality of electrodes.
 6. The apparatus of claim 1,wherein at least one sac is provided on either or both jaws, or onportions of one or both jaws.
 7. The apparatus of claim 1, wherein saidat least one electrode is formed on a surface of said sac.
 8. A methodfor effecting surgical electrocautery, comprising the steps of:providing a device having a pair of opposing jaws that are movablebetween an open position and a closed, clamping position; associating atleast one electrode with one of said jaws, said at least one electrodebeing disposed between said jaws for contact with a tissue surface;associating at least one sac with one of said jaws and positionedbetween said jaw and said at least one electrode to support said atleast one electrode; containing an incompressible fluid contained withinsaid at least one sac, wherein said sac is prefilled with saidincompressible fluid; wherein said at least one electrode exertspressure upon said at least one sac when said jaws are moved to aclosed, clamping position and said at least one electrode is broughtinto contact with said tissue surface, displacing said fluid within saidat least one sac, wherein said at least one electrode conforms to saidtissue surface while exerting an equal pressure along an entire lengthof said tissue surface.
 9. An apparatus for surgical electrocautery,comprising: a pair of opposing jaws that are movable between an openposition and a closed, clamping position; at least one electrodeassociated with one of said jaws, at least one electrode being disposedbetween said jaws for contact with a tissue surface; at least oneconformance member associated with one of said jaws, positioned betweensaid jaw and said at least one electrode to support said at least oneelectrode; wherein said at least one electrode exerts pressure upon saidat least one conformance member when said jaw is moved to a closed,clamping position and said at least one electrode is brought intocontact with said tissue surface, and wherein said at least oneelectrode conforms to said tissue surface while exerting an optimizedpressure along an entire length of said tissue surface; wherein saidconformance member comprises at least one sac associated with one ofsaid jaws, positioned between said jaw and said at least one electrodeto support said at least one electrode; and an incompressible fluidcontained within said at least one sac, wherein said sac is prefilledwith said incompressible fluid.
 10. The apparatus of claim 9, whereinsaid at least one electrode is formed on the surface of said sac. 11.The apparatus of claim 9, wherein said conformance member comprises aresilient member underlying said at least one sac.
 12. The apparatus ofclaim 9, wherein said conformance member compensatorily increases involume to maintain pressure on tissue as said tissue electrocauterizesand shrinks.
 13. An apparatus for surgical electrocautery, comprising: apair of opposing jaws that are movable between an open position and aclosed, clamping position; at least one electrode associated with one ofsaid jaws, said at least one electrode being disposed between said jawsfor contact with a tissue surface; at least one sac associated with oneof said jaws and positioned between said jaw and said at least oneelectrode to support said at least one electrode, said sac comprising atleast one partition defining at least two sac portions; anincompressible fluid contained within each sac portion of said at leastone sac, wherein said sac is prefilled with said incompressible fluid;wherein said at least one electrode exerts pressure upon said at leastone sac when said jaws are moved to a closed, clamping position and saidat least one electrode is brought into contact with said tissue surface,displacing said incompressible fluid within said at least one sac,wherein said at least one electrode conforms to said tissue surfacewhile exerting an optimized pressure along an entire length of saidtissue surface.
 14. The apparatus of claim 13, wherein said at least onepartition establishes a communicative fluid coupling between said atleast two sac portions.